Cellulosic structures



Patented Feb. 9, 1937 2,069,803 PATENT OFFICE CELLULOSIC STRUCTURES Winfield Walter Heckert, Ardentown, Del., as-

signor, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware N Drawing.

Application April 16, 1934, Serial- Claims.

This invention relates to cellulosic structures. such as filaments, threads, fabrics, sheets, films, caps, tubing or the like. More particularly, this invention relates to cellulosic structures of the type just mentioned characterized by a subdued or low luster and/or being more or less opaque.

In the ordinary methods of preparing cellulosic structures, such as filaments, threads, films caps, tubing, etc., from viscose, cuprammonium, nitrocellulose, cellulose acetate and other cellulosic solutions (without the addition of opaquing and/or low luster-inducing agents to the solution) the products are transparent or translucent and/or very highly lustrous. For many purposes,

transparency, brilliant sheen and luster are not desirable and thus restrict the uses of the material.

I have found that I can produce cellulosic structures of the type abovementioned and characterized by a subdued or low luster and/or being more or less opaque by incorporating therein an organic substance more fully explained hereafter. 1 1

The nature and objects of the invention will become apparent from the following description and appended claims.

In accordance with the principles of the instant invention, there is provided cellulosic structures, such as filaments, threads, films, caps, tubing or the like, having subdued or low lusters and/or being more or less opaque. These desiderata are secured, according to one phase of the invention, by incorporating in the solution from which the structure is to be produced a low luster-inducing agent of the type hereafter more fully explained.

The low luster-inducing agent contemplated by the instant invention is an organic polynuclear heterocyclic substance in which the hetero-atom or atoms are selected from group VI, sub-group B of the periodic table, that is, oxygen, sulphur, selenium and tellurium. One or more or all of thenuclei may be heterocyclic, and preferably 5 or 6 membered rings containing one or more hetero-atoms, and the remaining nuclei, if any, being carbocyclic rings, and preferably aromatic rings which may be attached by a single valence or condensed to the heterocyclic nucleus. Especially suitable are those compounds of the abovementioned type which contain a suflicient number of carbocyclic or hetcrocyclic nuclei highly deficient in hydrogen and having a refractive index diifering by at least 0.1, such as, for example, 0.15, 0.2, 0.3, 0.4 or indeed more, from the mean index of refraction of the substance constituting the mass of the cellulosic structure. Though heterocyclic compounds of the type herein referred to having one or two nuclei highly deficient in hydrogen may produce low luster products, much better results are secured when the heterocyclic compounds contain at least three nuclei highly deficient in hydrogen. The preferred compounds are white or substantially white crystalline solids having melting points substantially above ordinary temperatures, and preferably above C. So far as this invention is concerned, each closed chain of carbon or hetero-atoms or combination of carbon and hetero-atoms shall be considered as a nucleus. Thus, benzene, naphthalene and thianthrene have one, two and three nuclei respectively.

The specific low luster-inducing agents contemplated by the instant invention belong to the class which consists of condensed or non-condensed aromatic heterocyclic substances having present at least two, and preferably three or more, nuclei highly deficient in hydrogen in which the hetero-atom or atoms belong to the group consisting of oxygen, sulphur, selenium and tellurium, and in which the heterocyclic nuclei are selected from the group consisting of furane, thiophene, thioxane, dioxane and their sulphur, selenium and tellurium analogues and in which the aromatic nuclei are benzene, diphenyl or naphthalene nuclei, and the substantially colorless derivatives of these compounds, such as simple substitution products in which hydrogen is replaced by halogen, an alkyl group, a hydroxy alkyl group or a carbocyclic or heterocyclic nucleus.

As illustrative examples of compounds of the above mentioned type which have given satisfactory'results may be mentioned the following:

2. Polynuclear derivatives of thiophene (1) 2,4-diphenyl thiophene (2) Tetraphenyl thiophene (3) Dlnaphthyl thiophene (4) Dibenzothiophene (5) Alpha, alpha-dithienyl (6) Beta, beta-dithienyl (7) Alpha.beta-dithienyl (8) Triphenyl thienyl methane (9) Alpha-phenyl thiophene (10) Dithienyl methane (11) Trithienyl methane (12) Dithienyl ethylene (13) Alpha, beta-benzo thiophene (14) Beta, beta'-benzo thiophene (15) Alpha, beta-naphtho-alpha, beta-thiophene Phenanthro-isothiophene Di-peri-naphthylene thiophene Benzo-thiophene Benzo-dithiophene Thiophthene (21) Selenonaphthene 3. Polynuclear derivatives containing more than one hetero-atom Oxygen- (1) Benzo-1,4-dioxin (2) Di-benzo-1,4-dioxln Sulphur- (1) 2,5-diphenyl-1,4-dithiin (2) Thianthrene Oxygen and sulphur- (1) Dibenzo-1,4-oxthiin (2). Dinaphtho-1,4-oxthiin The refractive indices of a few of the foregoing specific compounds are as follows:

Iso-dinaphthalene oxide (At least 2 principal indices, approximately 1.65 and 1.79)

2,4-diphenyl thiophene (At least 2 principal indices, approximately 1.58 and 1.73)

Tetraphenyl thiophene (At least 2 principal indices, approximately 1.72 and 1.80)

(At least 2 principal indices, approximately 1.66 and 1.75 [estimatedh The mean refractive index of rayon produced by the viscose process is usually considered to be 1.535 (1.52 and 1.55), and the index of refraction of cellulose acetate rayon is 1.48.

The aforementioned low luster-inducing agents, which are white in color, possess a sufficiently low vapor pressure and are sufficiently inert to resist change or removal from the structure in the ordinary process of making and finishing the same during the manufacture thereof. They also effectively resist removal or change during any of the usual processes to which the finished structure may be subjected, such as boilingofi', dyeing, bleaching, ironing, etc. The substances are incompatible with the mass of the substance constituting the final product. Substances may be used which are soluble in the cellulosic solution but sufficiently incompatible with the cellulosic material to produce an opacifying and/or delus- "ering effect in the final product.

The low luster-inducing agent may be added Thianthrene to the cellulosic solution at any stage in the course of the preparation of the solution prior to the actual spinning or casting. It may be added directly, if the particle size is satisfactory, or after suitable adjustment of the particle size by any of the well-known methods, such as grinding in a colloid mill or pebble mill or in the form of a suspension or emulsion prepared with or without the assistance of suitable .dispersing agents or protective colloids, such as soaps, sulphonated oils, alkyl naphthalene sulphonic acid salts (Nekal), sodium caseinate, etc. or combinations thereof. The low luster-inducing agent may be completely insoluble in the solution or it may be soluble therein. If desired when a soluble agent is used, it may be dissolved in one or all of the solvents previous to the preparation of the cellulosic solution. Likewise, it may be incorporated in the solution simultaneously with the cellulose derivative.

The quantity of low luster-inducing agents which may be used may vary within wide limits, depending principally upon the opaquing and the luster desired in the final product. Cellulosic structures containing these low luster and/or opaquing agents in amounts ranging from 0.1% to 15% by weight have given satisfactory results. It is obvious, of course, that smaller or larger quantities may be employed as desired. When a viscose solution is employed, satisfactory results may be secured if it contains 7% cellulose and from 0.01% to 1.5% more or less of the low lusterinducing agent and/or opaquing agent.

The low luster-inducing agents contemplated by the instant invention may be used in combination with each other and/or with other low luster-inducing agents, such as mineral oil, petroleum jelly, waxes, parafifins, benzene, toluene, pine oil, or inorganic pigments, such as titanium dioxide, lithopone, zinc sulphide, etc.

In order to more fully explain the principles of this invention, the following illustrative examples are given. It is to be understood that these examples do not in any way restrict the invention but merely illustrate several specific and preferred embodiments which have given satisfactory results.

Example 1.--20 pounds of iso-dinaphthalene oxide are ground in a colloid mill with 40 pounds of water and 0.4 pound of sodium caseinate until most of the particles are below 1 micron in diameter. The slurry is diluted with 5 parts of water and allowed to settle for 18 hours at a depth of 5 inches. The top 4 inches of liquid are carefully decanted and are found to contain very few particles above 4 microns in diameter, most of the particles being 1 micron in diameter or below. This suspension is analyzed (4-5%) and used in making up viscose from the xanthate and sodium hydroxide. Enough suspension is employed to yield a final viscose solution containing 7% cellulose, 6% NaOH and 0.5% iso-dinaphthalene oxide.

The iso-dinaphthalene oxide is thoroughly incorporated and distributed throughout the viscose during the mixing operation. The viscose is filtered, ripened and spun or cast in the usual way. 5

Example 2.-A suspension of finely divided thianthrene is prepared in the same manner as described in Example 1 for iso-rdinaphthalene oxide. This suspension is added to and incorporated in viscose, using such amounts as to produce a solution containing 0.7% thianthrene, 7% cellulose, and 6% NaOH. The resulting viscose is processed, ripened, filtered, spun or cast. and

aoeasos the product purified and dried in the usual way.

Example 3.A slurry of 2,4-diphenylthiophene prepared as described for iso-dinaphthalene oxide in Example 1 is coagulated by making slightly acidic with acetic acid. The product is filtered, pressed, and dried. 10 pounds of the dry material are dispersed in 30 pounds of 3% cellulose acetate in acetone-alcohol solution by grinding in a pebble mill. This suspension is used in' making up a cellulose acetate solution containing 25% cellulose acetate and 1% 2,4- diphenylthiophene. The solution is then processed and spun, either "by the dry or wet spinning process, in the usual way.

Example 4.A suspension of tetraphenylthiophene is prepared as. described for 2,4-diphenylthiophene in Example 3. This suspension is used in making up a cellulose acetate solution containing 25% cellulose acetate and 2.5% tetraphenylthiophene. The solution is then processed and spun, either by the dry or wet spinning process, in the usual way.

Though the preferred embodiments of this invention contemplate the incorporation of the low luster-inducing agent in the solution at some time prior to extrusion or casting thereof, satisfactory results may be secured also by applying the low luster-inducing agent to a previously formed cellulosic structure. In other words, the low luster-inducing agent may be incorporated in the final cellulosic structure by an after treatment.

Though the invention has been specifically described in connection with the viscose and cellulose acetate processes, it is obvious that the principles thereof are equally applicable to the cuprammonium and cellulose nitrate processes.

Since it is obvious that various changes may be made in the specific detailsfhereinabove set forth, this invention is not restricted thereto except as set forth in the appended claims.

I claim:

1. A regenerated cellulose structure containing an aromatic heterocyclic compound in which the heterocyclic nucleus is of the class which consists of furane, thiophene, thioxane, dioxane, the sulphur, selenium and tellurium analogues thereof and the substantially colorless derivatives thereof secured when hydrogen is replaced by halogen, an alkyl group, a hydroxy alkyl group, a carbocyclic or heterocyclic nucleus,\the said aromatic heterocyclic compound being present in an amount to impart a low luster to the product.

2. A regenerated cellulose structure containing a condensed aromatic heterocyclic compound in which the heterocyclic nucleus is of the class which consists of furane, thiophene, thioxane, dioxane,

rivatives thereof secured when hydrogen is replaced by halogen, an alkyl group, a hydroxy alkyl group, a carbocyclic or heterocyclic nucleus, the said aromatic heterocyclic compound being present in an amount to impart a'low luster to the product.

4. A regenerated cellulose structure containing iso-dinaphthalene oxide in an amount to impart a low luster to the product.

5. A regenerated cellulose structure containing tetraphenyl thiophene in an amount to impart a low luster to the product.

6. Artificial thread formed of regenerated cellulose and containing an aromatic heterocylic compound in which the heterocyclic nucleus is of the class which consists of furane, thiophene, thioxane, dioxane, the surphur, selenium and tellurium analogues thereof and the substantially colorless derivatives thereof secured when hydrogen is replaced by halogen, an alkyl group, a hydroxy alkyl group, a carbocyclic or heterocyclic nucleus, the said aromatic heterocyclic compound being present in an amountto impart a low luster to the product.

7. Artificial thread formed of regenerated cellulose and containing a condensed aromatic hetgroup, a hydroxy alkyl group, a carbocyclic or heterocyclic nucleus, the said aromatic heterocyclic compound being present in an amount to impart a low luster to the product.

8. Artificial thread formed of regenerated cellulose and containing a non-condensed aromatic heterocyclic compound in which the heterocyclic nucleus is of the class which consists of furnace,-

lulose and containing tetraphenyl thiophene in an amount to impart a low luster to the product.

v LD WALTER HECKEBT.

CERTIFICATE OF CORRECTION.

Patent No. 2,969,803. February 9, 19371,;

wmno WALTER HECKERTO It is hereby certified that. error appears in the printed specification of the above numbered patentrequiring correction as follows: Page 3, second column, line 25, claim 6, for "s'urphur" read sulphur; line 48, claim 8, for "furnace" reed furane; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent office.

1 signed and, sealed this 23rd oiay of March, A. Do 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents. 

